
var xhr ; 
	function createxhr(){
		if(window.ActiveXObject)
		{
			xhr = new ActiveXObject("Microsoft.XMLHTTP");
		}else
		{
			xhr = new XMLHttpRequest(); 
		}
	}
	
	
function ajaxDo(url){
alert(url);
	createxhr() ; 
	xhr.open("GET",url); 
	xhr.onreadystatechange = function() 
	{
		if(xhr.readystate==4)
		{
			if(xhr.status==200) 
			{
				var key = xhr.responseText ;
				callBack(key);
			}
		}
	}
	xhr.send(null) ;
} 